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Biomedical subjects

T Lecompte

Publications and source records attributed to T Lecompte.

At least 109 records · Page 6Linked to original sources
PubMed1990

Genetic thrombocytopenia with an autosomal dominant transmission: a study of 54 cases.

On the basis of a retrospective study of 3,600 platelet kinetic studies, we have isolated 54 cases with chronic thrombocytopenia, a normal autologous and homologous platelet lifespan, and increased mean platelet volume without Döhle bodies, the absence of any functional platelet abnormalities, and a normal megakaryocyte count. These cases were either discovered during the first few years of life (i.e. constitutional) and/or were proven to be familial (autosomal dominant transmission). Previous treatments (corticosteroids, immunoglobulins, androgens, immunosuppressor agents, splenectomy) were not effective in any of these cases or in their relatives. A new syndrome can therefore be proposed which can be easily suspected in cases of early onset in life, increased platelet volume, failure of corticosteroids or evidence of a familial blood disorder. It can be proved when the autologous platelet life span is demonstrated to be normal in spite of a chronic thrombocytopenia and a normal megakaryocytic count. The recognition of this syndrome will avoid neonatal complications (cephal-hematomas), surgical complications, and the use of expensive and possibility harmful ineffective treatments, both in the propositus and in other abnormal family members. The syndrome is certainly frequent (54 families are presented here), but the diagnosis is often missed or delayed due to the low risk of hemorrhage. However, it is associated with a certain risk of leukemia (4 cases in 3 families).

Blood Platelets↗
PubMed1989

Chronic pure thrombocytopenia in elderly patients. An aspect of the myelodysplastic syndrome.

From a group of 276 elderly patients studied in the last 12 years in a department of nuclear medicine for investigating a chronic thrombocytopenia, 36 patients have an acquired disorder, with normal platelet life span, a normal megakaryocytic bone marrow count, and absence of any evident cause at the time of clinical evaluation. During the 2 to 10 subsequent years, 16 patients developed symptoms of the myelodysplastic syndrome, i.e., chronic aregenerative anemia, granulocytopenia, dysmyelopoiesis, and appearance of circulating blast cells; three of them died from acute myeloblastic leukemia. So a pure thrombocytopenia due to a platelet production defect, without any demonstrated functional platelet defect or morphologic dysmegakaryocytosis, may be a preleukemic syndrome. In the other 20 patients, with the same pure chronic thrombocytopenia, no malignant evolution has been seen with long follow-up delays, which is often also the case in pure refractory anemias. In the absence of objective criteria of a possible premalignant disorder, the classification of these cases is difficult, which it is also the case for the so-called refractory anemias. We suggest to individualize, in the classification of the myelodysplastic syndromes, a group of pure refractory thrombocytopenias. From a practical point of view such a diagnosis may be useful, at least to avoid inefficient and possibly harmful treatments.

Aged↗
PubMed1989

Calcium rise in human platelets elicited by anti-CD9 and -CD41 murine monoclonal antibodies.

Three murine monoclonal antibodies (anti-CD9: ALB6, anti-CD41: VI-PL3 and PL2-49/GPIIb - final concentration: 7.5 micrograms/mL) are shown to elicit after a lag time aggregation of washed platelets and a calcium signal (as detected by light emitted by loaded aequorin), which is only partially inhibited by aspirin. By comparison the rise induced by thrombin is greater and almost instantaneous. In the presence of EGTA a calcium mobilization from internal stores can be detected with thrombin and with ALB6, but neither with PL2-49 nor with VI-PL3, whereas platelets still change their shape and release ATP. It is tempting to speculate that although all the antibodies induce a calcium change, they activate platelets by different pathways: calcium may be not primarily involved in the activation induced by the anti-CD41 antibodies.

Adenosine Triphosphate↗
PubMed1989

PL2-49, a monoclonal antibody against glycoprotein IIb which is a platelet activator.

PL2-49 is a murine monoclonal IgG1 antibody obtained after immunization of Balb/c mice with EDTA washed platelets. Binding could be detected on Zwa(+) as well as Zwa(-) platelets, but not on type I Glanzmann's thrombasthenia platelets using an ELISA screening test. Immunoprecipitation studies showed that PL2-49 bound to glycoprotein IIb when the glycoprotein IIb/IIIa complex dissociation was performed after the monoclonal antibody binding. Experiments with a human alloantibody against Zwa antigen were run in parallel to control the complex dissociation. Ascitic fluid, as well as the purified antibody, induced activation and aggregation of washed platelets and ATP release. PL2-49-induced aggregation did not require exogenous fibrinogen and was inhibited, partially, in the presence of aspirin, apyrase, isosorbide dinitrate. Raising intra-platelet cyclic AMP with a stable PGI2 analogue, iloprost, and/or a phosphodiesterase inhibitor, RA 233, suppressed the responses to PL2-49. F(ab')2 fragments did not induce aggregation of normal platelets but inhibited the response to the whole immunoglobulin. Finally PL2-49 was shown to induce aequorin-detected elevations in intraplatelet Ca++ levels. Thus PL2-49 seems to differ from monoclonal antibodies so far described, since it binds to glycoprotein IIb in a complex-dependent manner at least under our experimental conditions for immunoprecipitation studies, and it induces platelet Ca++ mobilization and platelet aggregation after a lag-time. These reactions depend both on Fab and Fc domains of the antibody and require neither complement nor exogenous fibrinogen.

Animals↗
PubMed1989

Life-threatening intracranial bleeding associated with the presence of an antifactor VII autoantibody.

This is a report of a 62-year-old male patient who had a bleeding disorder due to the presence of a factor VII (proconvertin) inhibitor. After treatment with a high-dose intravenous (IV) immunoglobulin failed and a life-threatening intracranial hemorrhage occurred, plasma exchanges were performed and immunosuppressive therapy was given. The factor VII inhibitor promptly disappeared, and the patient's parameters of hemostasis became normal. Even though a relapse occurred some months later, the patient responded to immunosuppressive therapy. No underlying disorder was evidenced after 17 months of follow-up.

Autoimmune Diseases↗
PubMed1988

[Acquired factor VII inhibitor: treatment using high-dose immunoglobulins, corticotherapy and plasma exchange].

A 62 year old man presented a diffuse hemorrhagic syndrome related to the presence of an acquired factor VII inhibitor (proconvertin). Autoantibodies were of the IgG class and no subjacent disease was detected during a 7-month follow up. Treatment with high-dose polyvalent immunoglobulins was ineffective, and the onset of an intracerebral hemorrhage required therapy by a series of plasma exchanges combined with immunosuppressive treatment. The plasma inhibitor was no longer present after the first exchange and clinical and biological remission was rapid.

Cerebral Hemorrhage↗
PubMed1987

[Platelet aggregation tests in 26 cases of heparin-induced thrombopenia. Methodological, diagnostic problems and therapeutic aspects].

A diagnosis of heparin induced thrombocytopenia (HIT) in the 26 patients was based on: 1. normal platelet count prior to heparin administration; 2. its fall to less than 100 Giga/l (m = 46 +/- 23) at time of first sample collection for test to detect a platelet aggregation factor (PAF); 3. restoration of normal values after discontinuation of heparin treatment during which the thrombocytopenia had appeared. The result of the first PAF test in these 26 patients was positive in 22 cases, negative in 2; twice the plasma provoked platelet control aggregation without in vitro addition of heparin. The origin, dose and mode of administration of the heparin did not appear determinant in the production of the thrombocytopenia: 16 of the patients were later treated with a low molecular weight heparin (LMWH). An in vitro "compatibility" test was able to be performed 8 times previously and was negative in 7 cases in the 16 patients. Samples were collected during LMWH treatment and were negative in 13 cases, and this in agreement with the increased platelet count after 7 +/- 3 days and the clinical improvement. In 3 patients the test was positive: in one case the count did not return to normal, in the second case this did occur, but slowly (21 days); the PAF test in the last patient was positive prior to LMWH treatment and remained so while the count became normal. Concordance exists therefore between negativity of the test practiced with LMWH and the increase in count when this heparin is administered; inversely, the positivity of the test does not exclude normalization of the platelet count.

Adult↗